European regulators will spell out requirements for copies of antibody drugs next month, paving the way for generic competition in a multibillion-dollar market that includes treatments for cancer and immune system disorders.

European Medicines Agency (EMA) Executive Director Thomas Lonngren told Reuters on Friday that guidelines on biosimilar monoclonal antibodies would be published after being reviewed by the agency's expert committee on drug approvals in November.

The keenly awaited guidelines will then be open for three to six months of external consultation before being formally adopted, most likely in the second half of 2011, he said.

Up to now, complex biotech medicines have been generally immune from generic competition, unlike conventional pills and capsules. But the regulatory landscape is starting to change, posing a threat to leading biotech groups such as Roche Holding AG and Amgen Inc.

Europe has already approved 13 biosimilars, including copycat versions of human growth hormone, anemia treatment EPO and G-CSF against low white blood cell levels. Antibodies, however, are a far bigger prize and generic manufacturers are eager to cash in as patents on key products start to expire.

So far, the EMA has received requests for scientific advice on six biosimilar antibodies -- a relatively small number that reflects the difficulties of making such copycat medicines.

This is much more complicated than the normal generic business, so it will be a lot of work for these companies, said Lonngren, who expects around two or three applications a year.

CLINICAL TRIALS

As with the 13 existing biosimilar drugs approved by the EMA, generic companies will have to conduct clinical trials to prove their antibody is similar to the original product on which it is based. Clinical trials will be required, he said.

Lonngren declined to detail how extensive trials would have to be but said requirements were likely to be less onerous than in the United States, since the EMA will not give a view on whether biosimilars should be substitutable for the original.

U.S. regulatory preparations for biosimilar are further behind than in Europe, but leading generic drugmakers -- including Teva Pharmaceutical Industries, Novartis AG and Hospira Inc -- are eyeing opportunities in both markets.

Teva already has clinical studies under way comparing its copy of Roche's antibody drug Rituxan to the original in treating both rheumatoid arthritis and non-Hodgkin's lymphoma, a type of blood cancer.

The European patent on Rituxan, also known as MabThera, expires in 2014 and the drug could be the first antibody to face a cut-price biosimilar competitor. Rituxan had sales last year of 6.1 billion Swiss francs ($6.2 billion).

Worldwide sales of all biologic drugs reached some $130 billion in 2009, according IMS Health. With demand growing fast, the potential market for biosimilars could be worth tens of billion of dollars in the second half of the decade as multiple patents expire, industry analysts believe.

Medicine